Bartlett on Gardening: Loam Sweet Loam



If, like my friend June, you had to borrow a backhoe to prepare a garden spot last spring, you know improving your soil is not always easy. I used the above snap of June, and the slogan, on flyers for a program I did in 2003 on low-maintenance gardening.

I happen to know that June’s soil is a heavy acid clay. However, the pickax can be the cultivator of choice when dealing with very compacted soil or even subsoil. This last condition is common in the suburbs where developers remove the topsoil when grading lots.

It is rare to meet a gardener not trying to improve his soil. Is there an achievable ideal or are they engaged in an endless quest for an elusive grail? Loam soil is ideal for plant growth. It has a balance among the three particles that make up soil: sand, silt and clay. It is hard to have too much silt. Up to half of loam may be silt. It is equally easy to have too much clay. No more than about a quarter can be clay. The good news is that sand can be anywhere between a quarter and half the content.

Believe it or not, these particles need to have a certain amount of air around them. In a good and perfect world, the particles would make up almost half of the volume, air and water occupying a fourth each. The tiny remainder is made up of microorganisms and organic matter. When air space is reduced, drainage is impaired and plant roots cannot function properly. This condition is called “compaction.” We add to the problem by walking on and working the soil when it is wet. Too-frequent tilling can also lead to soil compaction.

When working to improve the soil, incorporating compost is a best practice. Compost improves fertility, drainage, soil structure and texture. It does take repeated additions of decayed organic material to change the structure of the soil. In an annual garden area, working in compost twice a year will yield noticeable improvement within a few seasons.


This year, we have had an abundance of rain. In our part of the world, rain delivers copious amounts of sulfur, which can lower soil pH. Most plants prefer slightly acid soil, 6.1 to 6.5 on the 14-point scale. In very acidic situations, phosphorous, calcium and magnesium become chemically bound and unavailable to plants. Using a pH meter, check around your garden and landscape to see if corrective action is needed. Agricultural limestone products are applied to raise pH. It takes months for the application to change the reading, so apply now as directed on the package to get ready for spring planting. Additionally, limestone aids in the development of good soil ​​​​structure by promoting aggregation of soil particles.

Autumn is the perfect time of year to prepare the soil for next year’s garden. Time is an essential element when adding amendments because it takes months for them to be absorbed into the soil.

Master gardener Ann Bartlett never lets lack of familiarity with a plant stop her from trying it in the ornamental beds around her home.


    Like what you read? Donate now and help me provide fresh news and analysis for my readers   

© 2016 by "Bien Design"